man3/__ppc_set_ppr_med.3

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  25 .TH __PPC_SET_PPR_MED 3 2017-09-15 "GNU C Library" "Linux\
  26 Programmer's Manual"
  27 .SH NAME
  28 __ppc_set_ppr_med, __ppc_set_ppr_very_low, __ppc_set_ppr_low, __ppc_set_ppr_med_low, __ppc_set_ppr_med_high \-
  29 Set the Program Priority Register
  30 .SH SYNOPSIS
  31 .B #include <sys/platform/ppc.h>
  32 .PP
  33 .B void __ppc_set_ppr_med(void);
  34 .br
  35 .B void __ppc_set_ppr_very_low(void);
  36 .br
  37 .B void __ppc_set_ppr_low(void);
  38 .br
  39 .B void __ppc_set_ppr_med_low(void);
  40 .br
  41 .B void __ppc_set_ppr_med_high(void);
  42 .SH DESCRIPTION
  43 These functions provide access to the
  44 .I Program Priority Register
  45 (PPR) on the Power architecture.
  46 .PP
  47 The PPR is a 64-bit register that controls the program's priority.
  48 By adjusting the PPR value the programmer may improve system
  49 throughput by causing system resources to be used more
  50 efficiently, especially in contention situations.
  51 The available unprivileged states are covered by the following functions:
  52 .IP * 3
  53 .BR __ppc_set_ppr_med ()
  54 sets the Program Priority Register value to
  55 .IR medium
  56 (default).
  57 .IP *
  58 .BR __ppc_set_ppr_very_low ()
  59 sets the Program Priority Register value to
  60 .IR "very low" .
  61 .IP *
  62 .BR __ppc_set_ppr_low ()
  63 sets the Program Priority Register value to
  64 .IR low .
  65 .IP *
  66 .BR __ppc_set_ppr_med_low ()
  67 sets the Program Priority Register value to
  68 .IR "medium low" .
  69 .PP
  70 The privileged state
  71 .IR "medium high"
  72 may also be set during certain time intervals by problem-state (unprivileged)
  73 programs, with the following function:
  74 .IP * 3
  75 .BR __ppc_set_ppr_med_high ()
  76 sets the Program Priority to
  77 .IR "medium high" .
  78 .PP
  79 If the program priority is medium high when the time interval expires or if an
  80 attempt is made to set the priority to medium high when it is not allowed, the
  81 priority is set to medium.
  82 .SH VERSIONS
  83 The functions
  84 .BR __ppc_set_ppr_med (),
  85 .BR __ppc_set_ppr_low ()
  86 and
  87 .BR __ppc_set_ppr_med_low ()
  88 are provided by glibc since version 2.18.
  89 The functions
  90 .BR __ppc_set_ppr_very_low ()
  91 and
  92 .BR __ppc_set_ppr_med_high ()
  93 first appeared in glibc in version 2.23.
  94 .SH ATTRIBUTES
  95 For an explanation of the terms used in this section, see
  96 .BR attributes (7).
  97 .ad l
  98 .TS
  99 allbox;
 100 lbw26 lb lb
 101 l l l.
 102 Interface       Attribute       Value
 103 T{
 104 .BR __ppc_set_ppr_med (),
 105 .br
 106 .BR __ppc_set_ppr_very_low (),
 107 .br
 108 .BR __ppc_set_ppr_low (),
 109 .br
 110 .BR __ppc_set_ppr_med_low (),
 111 .br
 112 .BR __ppc_set_ppr_med_high ()
 113 T}      Thread safety   MT-Safe
 114 .TE
 115 .ad
 116 .SH CONFORMING TO
 117 These functions are nonstandard GNU extensions.
 118 .SH NOTES
 119 The functions
 120 .BR __ppc_set_ppr_very_low ()
 121 and
 122 .BR __ppc_set_ppr_med_high ()
 123 will be defined by
 124 .I <sys/platform/ppc.h>
 125 if
 126 .B _ARCH_PWR8
 127 is defined.
 128 Availability of these functions can be tested using
 129 .BR "#ifdef _ARCH_PWR8" .
 130 .SH SEE ALSO
 131 .BR __ppc_yield (3)
 132 .PP
 133 .IR "Power ISA, Book\ II - Section\ 3.1 (Program Priority Registers)"